JP2532108B2 - Information recording member - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an information recording member in which information can be rewritten by irradiation of an energy beam such as a light beam or an electron beam. The present invention relates to a recording member utilizing a change in reflectance due to a phase change between crystals in a poor crystallinity state.

[Conventional technology]

The recording / reproducing method in the conventional phase change type optical disk medium is as described in JP-A-59-71140.
For recording, the beam spot is fully converged and irradiated for a short time.
Recording is erased by making the recording film completely amorphous by rapid heating and quenching, and recording is erased by gradually heating using an oval spot that is long in the track direction. Was carried out by returning to a completely crystalline state. Thus, two different beam spots are used for recording and erasing. This is because the time required for erasing is longer than the time required for recording. That is, the crystallization time of the recorded portion is long. However, recently, Applied Physics Letters Vol. 50 11
1987, pp. 667-669 (Appl.Phys.Lett.50 (1
1) As shown in 1987. pp. 667-669), a high-speed erasable recording film has been developed that can be crystallized in about the same time as the laser irradiation time required for recording. By using this film, it is possible to rewrite information with a single beam spot while the optical disk substrate makes one rotation only by changing the laser power.

[Problems to be solved by the invention]

Using the above-mentioned conventional recording film, overwriting with a single laser and a single light spot is possible, but in order to increase the rotational speed of the disk to increase the linear velocity and realize a high information transfer rate, It is necessary to further shorten the crystallization time.

An object of the present invention is to further shorten the crystallization time as compared with the conventional case.

[Means for solving problems]

The above object is achieved by providing a polycrystalline film in contact with the recording film.

Here, the polycrystalline film refers to a film formed by gathering the same crystal in various orientations. With a material that is easily crystallized, it is formed without heating the substrate using an ordinary sputtering device. You just get it.

As this polycrystalline film, a film such as ZnO and ZnS that does not undergo evaporation / melting / deformation due to laser irradiation or the like and is not affected by expansion or contraction of the recording film, that is, has a high melting point and Use a film with high hardness. The preferable range of the crystal size of the polycrystalline film is 5 nm or more and 100 nm or less, and more preferably 5 nm or more and 50 nm or less. The thickness of the polycrystalline film is preferably 10 nm to 1 μm, more preferably 100 nm to 400 nm.
The polycrystalline film is preferably transparent.

Further, as the recording film used in the present invention, it is desirable that the shortest crystallization time during laser light irradiation is 1 μs or less and the crystallization temperature is 200 ° C. or higher. Further, if the film structure is the same as that of the polycrystalline film, the crystallization time can be further shortened.

[Action]

When information is recorded on a crystallized recording film by irradiation with high power laser light or the like, that portion becomes amorphous or has poor crystallinity. Next, when this recorded portion is erased by irradiation with low power laser light or the like, the original crystalline state is restored. At this time, if there is a polycrystalline film in contact with the recording film, the recording film is likely to be crystallized under the influence of the polycrystalline film. That is, the time required to shift from the amorphous or poorly crystalline state to the crystalline state is shortened.

This polycrystalline film is effective because it shortens the crystallization time and has an effect as a reflective layer or a protective layer.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to Examples.

FIG. 1 is a structural cross-sectional view of the optical disk in this embodiment.

First, a base film 2 having a groove for tracking was formed on a glass substrate 1 having a diameter of 5 inches by using an ultraviolet curable resin. And on top of this ZnO by ion beam sputtering
The film 3 was formed to a thickness of 100 nm. This ZnO film 3 has a melting point of 18
It is as high as 00 ℃, and because it is almost transparent and the crystal size is small,
It is most suitable for the polycrystalline film used in the present invention. This ZnO
An Sn-Te-Se based recording film 4 having a thickness of 100 nm is formed on the film 3 as an optical recording film.
Deposited to a thickness of. Finally, the protective film 5 has a thickness of about 100μ.
m ultraviolet curable resin layer was provided. In the disk medium having such a structure, the semiconductor laser light sufficiently converged from the substrate 1 side by the focusing lens 6 is held on the groove for tracking, and the recording film 4 has a diameter of 1 μm while performing automatic focusing.
A recording portion of about m was formed. The erasing was performed by heating the recorded portion to a temperature slightly lower than the melting point with a semiconductor laser beam. At this time, the erase time is one digit or more (up to 1 μs or less) as compared with the conventional disk without the ZnO film 3.
I knew it would be shorter. In addition, the erase time can be shortened even in the disk structure in which the optical recording film 4 and the ZnO film 3 are formed in the reverse order as shown in FIG. 2 and the structure in which the optical recording film 4 is sandwiched by the ZnO film 3 as shown in FIG. We were able to.

In this embodiment, a transparent film such as the ZnO film 3 is used as the polycrystalline film, but an opaque film such as Pd or Pt has the same effect. Further, since these opaque films also have an effect as a reflection layer, they are useful for improving recording sensitivity and shortening erasing time.

It is preferable that the crystal grains used for these are small in size because electrical noise is small, but if it is less than 5 nm, the effect of shortening the erasing time becomes weak.

〔The invention's effect〕

According to the present invention, the time required to shift from the amorphous (recording) state to the crystalline (erase) state, that is, the crystallization (erase) time can be shortened, so that the information transfer rate can be increased. Further, since this polycrystalline film also has an effect as a reflection layer or a protective layer, it is useful for improving reliability.

[Brief description of drawings]

1, 2 and 3 are longitudinal sectional views of an optical disk in an embodiment of the present invention. 1 ... Glass substrate, 2 ... Base film, 3 ... Polycrystalline film, 4
...... Optical recording film, 5 ...... Protective film, 6 ...... Convergence lens.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keikichi Ando 1-280, Higashi-Kengokubo, Kokubunji, Tokyo (56) References JP-A-62-22249 (JP, A) JP-A-62-22249 62-247791 (JP, A)

Claims (1)

(57) [Claims] 1. A recording member in which information can be rewritten by irradiation of an energy beam, wherein a polycrystalline film having a crystal grain size of 5 nm or more and 100 nm or less is provided in contact with the recording film. Parts.